Underwater cameras are well-known and have been used for many years in both scientific, recreational, and commercial underwater exploration. During more recent times, the use of underwater television cameras has become an increasingly important and desirable tool in underwater exploration.
In attempting to locate underwater objects, or to study underwater geography, it is often necessary to explore large geographic areas. By utilizing television cameras, observers in a surface vessel may visually examine the underwater surroundings as seen by the camera without waiting for the bringing back of the camera by the diver and for the developing of the film. Further, the use of television cameras in underwater applications permits remote control camera operation. Remote operation of the camera is very desirable since the underwater applications are not then limited by a diver's air supply or by the physical capabilities of underwater divers in controlling the camera.
The use of color television in underwater exploration is particularly desirable since the identification of colors increases the ability to detect contrasts and to better identify and understand the physical makeup of the object being viewed.
With the more recent advent of deep-water oil exploration and drilling, as well as other high-pressure (also often referred to as "dense shielding") underwater activities, the use of remotely controlled television cameras has become increasingly important. In fact, underwater television cameras comprise a very necessary part of the conducting of thorough and reliable deep-water exploration.
It is well-known that water pressure increases rapidly with depth, and thus unprotected divers cannot operate at depths greater than several hundred feet below the water surface. However, deep-water exploration and similar activities may require examination of subjects at depths in excess of 2,500 feet below the water surface. It is impossible to provide manual operation of television cameras by divers at such depths. Thus, used in conjunction with specialized underwater vehicles, remotely operated underwater television cameras thus provide the only practical means by which the subjects of deep-water exploration may be visually inspected.
Due to the effects of water pressure, even at depths of only a few hundred feet, the sizes and shapes of camera housings available for underwater use have been very restricted in the past. As a necessary result, the possible configurations of the television cameras used in underwater applications have been restricted by the design limitations of the housing. This restriction has been particularly limiting on the ability to use those types of color television cameras and associated equipment which provide the highest quality picture and color resolution. This is a very undesirable limitation due to the fact that an important feature of exploration in deep and often cloudy water is the ability to clearly view the configuration and color composition of structures present in the area of exploration. Accordingly, this limitation has comprised a major handicap in the ability to conduct efficient and thorough deep-water exploration.
Because of the above factors, up to the present time, the types of color television cameras which could be used in underwater applications were restricted to stacked tube camera embodiments. In these camera embodiments, the three color tubes (red, blue, and green) are configurated in axial alignment with the camera body, in a "stacked" relationship. In creating this relationship, several prisms are required for separating the colors in the light received through the lens and for directing each separated color to its respective axially aligned color tube.
The use of multiple prisms inherently causes a reduction in the picture quality and resolution produced by the camera. Nevertheless, this camera design has necessarily been utilized since its configuration can be utilized in the only canister housing design available which could stand the high water pressures experienced in deep-water photography.
In addition to the necessary use of the stacked tube camera, prior art underwater color television camera systems have also been restricted by the housing size to use of a lens which is of a diameter not exceeding that of the camera body. Such lenses generally provide poor picture clarity and virtually always have focal lengths which require either remote or manual focusing in order to shift between subjects which are near the camera and those which are far away. The necessity for a diver or remote operator to be continually adjusting the camera focus is a great impediment to the ability to quickly obtain acceptable pictures of moving subjects or changing terrain.
In addition to problems in camera use as described above, camera maintenance and repair in prior art systems has been a continuing problem. In using the stacked tube camera, if a malfunction occurred, or if other service was required, the entire camera was necessarily removed from its housing or canister in order to make the required repairs. This disabled the full camera system until the repair, no matter how insignificant, had been completed.
A color television camera which has been heretofore used in the television broadcasting industry (and which would be very desirable for use in underwater environments) utilizes three separate color tubes, two of which are directed outward from the camera body. This "spread tube" arrangement in the television camera (sometimes referred to as a "three-tube camera") requires only a single prism for separating the colors and directing them to the proper tubes. Since incoming light passes through only a single prism, very good resolution of color is possible, and when this camera is coupled with a high quality lens, it produces a picture far superior to that from the stacked tube camera. Nevertheless, until the present time it has been impractical to utilize such a camera for essentially any underwater purpose because the canisters required to house the camera could not be adapted to operation at anything but near surface depths.
Prior to the present invention, the general feeling has been that a spread tube color television camera was not adaptable for use in underwater exploration since its irregular surface configuration would complicate maintenance problems even further. For example, use of a spread tube camera would require a very large canister in order to surround the tubes and camera. Although such a large cylindrically shaped canister could accomodate the spread tubes, significant structural support within the canister would be required to prevent the remainder of the camera from wobbling in an unstable and thus unusable fashion. The structure required for supporting and stabilizing the spread tube camera in such a housing would cause a problem with access to the camera for maintenance and repair. In addition, a cylindrical housing of a size which would accomodate such a camera would be very bulky and awkward for a diver to handle. Such a housing would necessarily be heavy in construction or would require numerous weight belts or like devices to displace the amount of water necessary for the weight of the camera system to be "neutral" in the underwater environment.
Alternatively, a canister which somewhat conforms to the camera structure could be used with no stability problems. However, the latter design would not permit removal of the camera from the canister housing for servicing and therefore, such a design would be clearly unworkable. Thus, until the present time, the use of such a spread tube camera in underwater applications has been considered by those skilled in the art to be impractical, if not impossible.
An additional problem experienced in prior art systems has been a significant reduction in picture quality which is experienced due to changes in functioning of electronic camera components in response to environmental changes such as temperature drops occurring on introduction of the camera into frigid waters.
Prior art underwater camera systems have been limited in the number of camera functions which could be remotely controlled. Thus, when electronic component performance changed during camera operation, the camera had to be brought to the surface, removed from its housing, and manually adjusted and tuned for proper function in its surrounding environment. Often, several repetitions of this procedure have been necessary to obtain proper adjustment in those conditions. Even then, if conditions change further, the procedure may have to be necessarily repeated again. This requirement of repeated surface adjustment of the camera components is very time consuming and clearly is an undesirable limitation which has continually presented problems and inconveniences in the prior art underwater camera systems.
In addition to considerations of camera size, shape and picture quality, another important aspect of deep water exploration is the ability to quickly analyze the pictures received and obtain data which is useful in identifying the particular structure or material being viewed. Prior applications have required constant visual monitoring by users, with a separate analysis of the results obtained. Furthermore, if the user was in fact a diver operating a camera, he did not have access to appropriate analytic tools while using the camera underwater.
Although prior art television cameras have been attached to monitoring equipment on the surface vessel, it has not been possible to accurately pinpoint the underwater location of the remotely operated camera other than by visually identifying surrounding geographic configurations. Thus, after identifying a particular structure which is of interest, it has been necessary to visually monitor the camera's view field and return the remotely controlled camera to the desired location by identification of the camera's surroundings. This procedure is cumbersome, time consuming, and expensive.
In light of the above considerations, it would be a great improvement in the art, as well as a solution to several longstanding problems in the art, to provide a color television camera which could produce high quality color resolution and picture quality when utilized in high pressure, or dense shielding, underwater applications. A further improvement in the art would be to provide such a camera which would permit quick and easy access for maintenance, and which could be removed from the canister housing in component parts so as to permit replacement of malfunctioning sections, thereby allowing for continued camera use during repair of the malfunctioning portions. Another improvement would be to provide an underwater camera whose components could be remotely adjusted and tuned so as to overcome adverse effects resulting from changes in the camera environment. A further improvement would be to provide an underwater color television camera which is interfaced directly with a computer for providing computer graphics capabilities and for permitting immediate surface use or underwater diver analysis of exploration findings, as well as for control of camera operation and navigation. A further important improvement in the art would be to provide computer character production capability for permitting visual communication of information from a surface vessel to a diver manually operating the camera in a water environment, thus providing analytic tools for use by the underwater diver.